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981.
In this paper, a simple sol–gel route has been adopted in developing substrate surface for the first time. Only by adjusting the concentration of precursor solution, LaAlO3 (LAO) nanodot arrays were directly obtained on LAO single crystal substrate, without incorporating additional processing steps. Subsequently, YBa2Cu3O7?x (YBCO) superconducting films were prepared on the nanodot arrays using a low-fluorine solution process. In contrast, J c of YBCO films grown on the substrate developed with nanodot arrays is almost three times as large as that of YBCO films grown on undeveloped substrate in an applied magnetic field with the strength of 3 Tesla. The pinning force density (F p ) of YBCO film on the nanodot arrays developed substrate is 2.7 GN/m3 which exceeds that (1.8 GN/m3) of YBCO films on undeveloped substrate. The results of cross-section transmission electron microscope (TEM) images show that the extended defects along the a–b planes of YBCO, induced by the developed substrate with nanodot arrays, should be the origin of the J c enhancement. 相似文献
982.
Dr. Samir Safi Dr. Gaëlle Creff Dr. Aurélie Jeanson Lei Qi Christian Basset Dr. Jérome Roques Dr. Pier Lorenzo Solari Prof. Eric Simoni Dr. Claude Vidaud Prof. Christophe Den Auwer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(34):11261-11269
Herein, we describe the structural investigation of one possible uranyl binding site inside a nonstructured protein. This approach couples spectroscopy, thermodynamics, and theoretical calculations (DFT) and studies the interaction of uranyl ions with a phosphopeptide, thus mimicking a possible osteopontin (OPN) hydroxyapatite growth‐inhibition site. Although thermodynamical aspects were investigated by using time‐resolved laser fluorescence spectroscopy (TRLFS) and isothermal titration calorimetry (ITC), structural characterization was performed by extended X‐ray absorption fine structure (EXAFS) at the U LIII‐edge combined with attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy. From the vibrational and fluorescence spectra, several structural models of a UO22+/peptide complex were developed and subsequently refined by using theoretical calculations to fit the experimental EXAFS obtained. The structural effect of the pH value was also considered under acidic to moderately acidic conditions (pH 1.5–5.5). Most importantly, the uranyl/peptide coordination environment was similar to that of the native protein. 相似文献
983.
984.
Dr. Hui Cai Zhan‐Yi Sun Zhi‐Hua Huang Lei Shi Prof. Dr. Yu‐Fen Zhao Prof. Dr. Horst Kunz Prof. Dr. Yan‐Mei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(6):1962-1970
Glycopeptides of tumor‐associated mucin MUC1 are promising target structures for the development of antitumor vaccines. Because these endogenous structures were weakly immunogenic, they were coupled to immune‐response‐stimulating T‐cell epitopes and the Pam3Cys lipopeptide to induce strong immune responses in mice. A new thioether‐ligation method for the synthesis of two‐ and three‐component vaccines that contain MUC1 glycopeptides as the B‐cell epitopes, a T‐cell epitope peptide, and the Pam3CSK4 lipopeptide is described. The resulting fully synthetic vaccines were used for the vaccination of mice, either in a liposome with Freund′s adjuvant or in aqueous PBS buffer. The three‐component vaccines that contained the Tetanus Toxoid P2 T‐cell epitope peptide induced strong immune responses, even when administered just in PBS. By activation of the complement‐dependent cytotoxicity (CDC) complex, the antisera induced the killing of tumor cells. 相似文献
985.
Dr. Yaqi Jiang Yanyan Jia Jiawei Zhang Lei Zhang Huang Huang Prof. Dr. Zhaoxiong Xie Prof. Dr. Lansun Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3119-3124
Pt? Cu alloy octahedral nanocrystals (NCs) have been synthesized successfully by using N,N‐dimethylformamide as both the solvent and the reducing agent in the presence of cetyltrimethylammonium chloride. Cu underpotential deposition (UPD) is found to play a key role in the formation of the Pt? Cu alloy NCs. The composition in the Pt? Cu alloy can be tuned by adjusting the ratio of metal precursors in solution. However, the Cu content in the Pt? Cu alloy NCs cannot exceed 50 %. Due to the fact that Cu precursor cannot be reduced to metallic copper and the Cu content cannot exceed 50 %, we achieved the formation of the Pt? Cu alloy by using Cu UPD on the Pt surface. In addition, the catalytic activities of Pt? Cu alloy NCs with different composition were investigated in electrocatalytic oxidation of formic acid. The results reveal that the catalytic performance is strongly dependent on Pt? Cu alloy composition. The sample of Pt50Cu50 exhibits excellent activity in electrocatalytic oxidation of formic acid. 相似文献
986.
Qian Lei Yawen Wei Dinesh Talwar Prof. Chao Wang Prof. Dong Xue Prof. Jianliang Xiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(12):4021-4029
Reductive amination of various ketones and aldehydes by transfer hydrogenation under aqueous conditions has been developed, by using cyclometallated iridium complexes as catalysts and formate as hydrogen source. The pH value of the solution is shown to be critical for a high catalytic chemoselectivity and activity, with the best pH value being 4.8. In comparison with that in organic solvents, the reductive amination in an aqueous phase is faster, and the molar ratio of the substrate to the catalyst (S/C) can be set as high as 1×105, the highest S/C value ever reported in reductive amination reactions. The catalyst is easy to access and the reaction is operationally simple, allowing a wide range of ketones and aldehydes to react with various amines in high yields. The protocol provides a practical and environmental friendly new method for the synthesis of amine compounds. 相似文献
987.
Dennis Cao Dr. Michal Juríček Zachary J. Brown Dr. Andrew C.‐H. Sue Dr. Zhichang Liu Juying Lei Anthea K. Blackburn Dr. Sergio Grunder Dr. Amy A. Sarjeant Prof. Ali Coskun Prof. Cheng Wang Prof. Omar K. Farha Prof. Joseph T. Hupp Prof. J. Fraser Stoddart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8457-8465
We report the synthesis of two [2]catenane‐containing struts that are composed of a tetracationic cyclophane (TC4+) encircling a 1,5‐dioxynaphthalene (DNP)‐based crown ether, which bears two terphenylene arms. The TC4+ rings comprise either 1) two bipyridinium (BIPY2+) units or 2) a BIPY2+ and a diazapyrenium (DAP2+) unit. These degenerate and nondegenerate catenanes were reacted in the presence of Cu(NO3)2?2.5 H2O to yield Cu‐paddlewheel‐based MOF‐1050 and MOF‐1051. The solid‐state structures of these MOFs reveal that the metal clusters serve to join the heptaphenylene struts into grid‐like 2D networks. These 2D sheets are then held together by infinite donor–acceptor stacks involving the [2]catenanes to produce interpenetrated 3D architectures. As a consequence of the planar chirality associated with both the DNP and hydroquinone (HQ) units present in the crown ether, each catenane can exist as four stereoisomers. In the case of the nondegenerate (bistable) catenane, the situation is further complicated by the presence of translational isomers. Upon crystallization, however, only two of the four possible stereoisomers—namely, the enantiomeric RR and SS forms—are observed in the crystals. An additional element of co‐conformational selectivity is present in MOF‐1051 as a consequence of the substitution of one of the BIPY2+ units by a DAP2+ unit: only the translational isomer in which the DAP2+ unit is encircled by the crown ether is observed. The overall topologies of MOF‐1050 and MOF‐1051, and the selective formation of stereoisomers and translational isomers during the kinetically driven crystallization, provide evidence that weak noncovalent bonding interactions play a significant role in the assembly of these extended (super)structures. 相似文献
988.
Feng Zou Prof. Xianluo Hu Dr. Yongming Sun Dr. Wei Luo Fangfang Xia Long Qie Yan Jiang Prof. Yunhui Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6027-6033
Zn2GeO4/N‐doped graphene nanocomposites have been synthesized through a fast microwave‐assisted route on a large scale. The resulting nanohybrids are comprised of Zn2GeO4 nanorods that are well‐embedded in N‐doped graphene sheets by in situ reducing and doping. Importantly, the N‐doped graphene sheets serve as elastic networks to disperse and electrically wire together the Zn2GeO4 nanorods, thereby effectively relieving the volume‐expansion/contraction and aggregation of the nanoparticles during charge and discharge processes. We demonstrate that an electrode that is made of the as‐formed Zn2GeO4/N‐doped graphene nanocomposite exhibits high capacity (1463 mAh g?1 at a current density of 100 mA g?1), good cyclability, and excellent rate capability (531 mAh g?1 at a current density of 3200 mA g?1). Its superior lithium‐storage performance could be related to a synergistic effect of the unique nanostructured hybrid, in which the Zn2GeO4 nanorods are well‐stabilized by the high electronic conduction and flexibility of N‐doped graphene sheets. This work offers an effective strategy for the fabrication of functionalized ternary‐oxide‐based composites as high‐performance electrode materials that involve structural conversion and transformation. 相似文献
989.
Dr. Qingsong Dong Prof. Xiao‐Juan Yang Shida Gong Dr. Qiong Luo Prof. Qian‐Shu Li Prof. Ji‐Hu Su Dr. Yanxia Zhao Prof. Biao Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(45):15240-15247
A nickel? nickel‐bonded complex, [{Ni(μ‐L.?)}2] ( 1 ; L=[(2,6‐iPr2C6H3)NC(Me)]2), was synthesized from reduction of the LNiBr2 precursor by sodium metal. Further controllable reduction of 1 with 1.0, 2.0 and 3.0 equiv of Na, respectively, afforded the singly, doubly, and triply reduced compounds [Na(DME)3] ? [{Ni(μ‐L.?)}2] ( 2 ; DME=1,2‐dimethoxyethane), [Na(Et2O)]Na[(L.?)Ni? NiL2?] ( 3 ), and [Na(Et2O)]2Na[L2?Ni? NiL2?] ( 4 ). Here L represents the neutral ligand, L.? denotes its radical monoanion, and L2? is the dianion. All of the four compounds feature a short Ni? Ni bond from 2.2957(6) to 2.4649(8) Å. Interestingly, they display two different structures: the perpendicular ( 1 and 2 ) and the coaxial ( 3 and 4 ) structure, in which the metal? metal bond axis is perpendicular to or collinear with the axes of the α‐diimine ligands, respectively. The electronic structures, Ni? Ni bonding nature, and energetic comparisons of the two structure types were investigated by DFT computations. 相似文献
990.